Expansion joint

ABSTRACT

An expandable track section particularly useful for joining sections of an electrical signal or power track. The expandable section comprising a track portion with numerous lateral slots on either side forming a zigzag member.

I United States Patent [151 3,637,957 Janzow et al. 1 Jan. 25, 1972 [54] EXPANSION JOINT 2,831,071 4/1958 Taylor ..191/44.1 2,896,009 7/1959 Caveney ,.l74/72 A [72] Inventors: Lester G. Janzow, Los Angeles; Ronald D.

Lipke, Sherman Oaks, both of Calif. FOREIGN PATENTS OR APPLICATIONS [73] Assignee: The Dashaveyor Company, Venice, Calif. 566,679 1/1945 Great Britain ..174/72 A [22] Filed: 1968 Primary Examiner-Arthu1' L. La Point [21] Appl. No.: 767,297 Assistant Examiner-George H. Libman Attorney-Lindenberg, Freilich & Wasserman [52] U.S. Cl ..l9l/29, 191/441, 174/99 E [57] ABSTRACT [51] Int. Cl. ..B60m l/02, B60m l/26 [58] Field of Search ..l74/13, 21.4, 99 E, 69, 72 A; An p n l rack se ion parti ularly useful for joining 339/9, 9 E; 191/22, 23, 29, 44.1; 267/180, 182 sections ofan electrical signal or power track. The expandable section comprising a track portion with numerous lateral slots [56] Referen e Cited on either side forming a zigzag member.

UNITED STATES PATENTS 6 Claims, 7 Drawing F g 1,101,579 6/1914 Steinberger ..19l/33 DM PATENTEU M25197? summer? INVENTOR5 XM4A 4MSM PATENTEDJANZSIQYZ 3537.957

sum 2 or z 68 Lzsree 6. Jmvzow/ Row/21.0 1) I, IP/(E INVENTORS 4r TOQALQ y 5 EXPANSION JOINT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to tracks for engaging elements of a vehicle.

2. Description of the Prior Art Electrically powered vehicles often receive currents from power tracks which extend along the vehicle route. The power tracks are engaged by shoes on the vehicle which slide along the track face. Track systems generally include numerous expansion joints which take up expansion and contraction cause by variations in ambient temperature. It is desirable that the joints provide a smooth path for the shoe, to prevent wear on it or the track, and that there be no gaps or areas of high resistance where arcing and hot spots may develop. One such joint is disclosed in U. S. Patent Application Ser. No. 758,321 filed Sept. 9, 1968 by Dashew and Janzow, which is assigned to the assignee of the present application.

OBJECTS AND SUMMARY OF THE INVENTION An object of the present invention is to provide a track expansion joint which supplies a very smooth path for vehicle elements.

Another object is to provide a current-carrying expansion joint which minimizes hot spots and arcing.

In accordance with the present invention, track expansion apparatus is provided which establishes a smooth path for vehicle elements. In one embodiment of the invention, the joint comprises a section of track with alternate lateral slots which fonn it into a zigzag shape. The joint section is placed in series with long lengths of ordinary track to take up expansion and contraction in them. A bracing bar is inserted into the joint section to support it against sagging and twisting. The bracing bar is fixed to one end of the joint section and can slide relative to the rest of it.

The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an expansion joint constructed in accordance with the invention, shown in a nearly fully contracted configuration;

FIG. 2 is a partial front elevation view of the expansion joint of FIG. 1;

FIG. 3 is a sectional side elevation view taken on the line 33 of FIG. 1;

FIG. 4 is a partial front elevation view, showing the expansion joint of FIG. 2 in an expanded configuration;

FIG. 5 is a simplified diagram showing the manner of manufacturing the expansion joint of FIG. 1;

FIG. 6 is a perspective exploded view of an expansion joint constructed in accordance with another embodiment of the invention; and

FIG. 7 is a sectional end view of the joint of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 through 4 illustrate an expansion joint section 10 for connection in series with two main power track sections 12 and 14. The face 16 of the track is engaged by a shoe 18 of a vehicle. The vehicle is propelled by an electric motor, and the shoe carries energizing currents from the track to the motor. The joint section 10 can expand and contract considerably in length to take up contractions and expansions, respectively, in the main track sections 12 and 14.

Both the main and joint tracks are of C cross section, with a base 20, flanges 22 and 24 extending rearwardly from the base, and lips 26 and 28 extending toward each other from the ends of the flanges. A multiplicity of lateral cuts or slots are formed in the joint section, to leave a member of zigzag form.

LII

Slot 30 extends laterally through the upper flange 22 and lip 26, and continues laterally through the base 20 down to a position near the lower flange 24. The slots 32 and 34 on either side of slot 30 extend in a complementary manner through the lower flange and through the base up to ,a position near the upper flange. Numerous other slots are spaced along the length of the track section, withalternate slots cut in a complementary manner.

When the main track sections 12 and 14 are subjected to low temperatures and they contract, the joint section 10 is subjected to tension. It expands to the configuration shown in FIG. 4, wherein the slots open and the small portions of track between the slots move away from each other.

Because of the series of slots in the joint section, it is weakened and could sag. Also, if not reinforced it could be deflected by the forceof the shoe 18, which may press with a force on the order of 30 pounds for a 2 inch wide track. In order to fix the position of the joint section, an insert or bracing bar 36 is provided. The bar has one end portion 38 fixed to both the main track section 12 and the end 40 of the joint section. The attachment is accomplished by a connecting plate 42 and four bolts 44 which extend through holes in the plate and engage threaded holes in the bracing bar. The rest of the bracing bar, including the opposite end 46, is free to slide within the joint section.

The opposite end portions 40 and 50 of the joint section are free of slots to strengthen them. These ends 40 and 50 are held to the main track sections by the connecting plate 42 and by another connecting plate 52 and 'a small additional insert bar 54. As the joint section expands or contracts, the bracing bar slides relative to it, providing support against sagging and against deflection away from the shoe, and also preventing twisting. To this end, the bracing bar 36 has a cross section closely mated to the free area within the C-shaped track, so it is adjacent to or engages the inner surface of the base and flanges of the track.

Even in a fully expanded configuration such as that shown in FIG. 4, only short gaps exist. This promotes smooth travel over the track. The area over which the shoe contacts the track surface 16 is decreased only a small percentage during passage over the expanded joint section. Thus, a low-resistance contact can be maintained. For signal-carrying tracks, this prevents large loss of signal power. For power tracks, this prevents arcing and the development of hot spots.

The tracks are preferably constructed of a material of high conductivity, such as aluminum. The slots can be formed by saws or other well-known apparatus. The slots preferably do not extend into or even nick the opposite flange, e.g., slot 30 preferably does not reach the lower flange 24. This is to reduce the chance of fatigue failure at the ends of the slots where high stresses may be produced during joint expansion. The large depth E of the flanges enables themto resist the high stresses. Fatigue failure may also be resisted by enlarging the ends of the slots, as by drilling holes at the ends.

In the manufacture of the joint section, it is desirable to round the walls of each slot to assure smooth shoe travel. This can be accomplished in the manner shown in FIG. 5, by bending the joint section so the front surface which contacts the vehicle shoe is convexly curved as shown at 16A. A rotating wire brush 60 is then passed along the surface. The brush removes burrs and slightly rounds the walls of the slot at the front joint surface. Tracks of aluminum constructed in accordance with the foregoing description, of 3% foot length with cuts spaced at zfi-inch intervals, have been found to readily expand 6 inches without damage.

FIG. 6 illustrates another form 'of expansion joint apparatus, which is suitable for use with the main track of C cross section described above, to tie two track sections 66 and 68 together. In the joint apparatus of FIG. 6, ajoint member 70 is provided which is of the same form as the bracing bar 36 described above, except that it has three elongated fingers 72, 74 and 76 that extend along the length of the bar. Three slots 78, 80 and 82 are formed in the end of the track section 66, at the face or base thereof, for receiving the three fingers of the joint member. One end portion 86 of the joint member, which is devoid of the fingers, can be received in the other track section 68, and is held therein by bolts that extend through a connecting plate 88 and through threaded holes 90 and 92 in the joint member. When the joint of FIG. 6 is assembled, the fingers 72 through 76 are held in the slots 78 through 82, and slide longitudinally therein to take up expansion and contraction in the track sections 66 and 68. The joint section 70, by fitting into the track section 66, holds the main track sections in alignment.

Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.

What is claimed is:

1. Expansion joint apparatus for track sections which engage a vehicle comprising:

an elongated member having a base defining a face for engaging an element of a vehicle and having a pair of flanges extending rearwardly from laterally opposite sides of said base, said member having a plurality of slots extending substantially laterally from one edge of the member to a position spaced from the opposite edge, with alternate slots formed complementary to each other, whereby to form a zigzaglike member; and

bracing bar means disposed within said elongated member,

including one end fixed with respect to one end of said elongated member and an opposite end portion in slideable engagement with said elongated member.

2. The expansion joint apparatus described in claim 1 wherein:

said elongated member has lips extending from the rearward ends of said flanges toward each other; and

said bracing bar means includes portions adjacent to the inner surfaces of the base, flanges and lips of said elongated member, whereby to resist twisting of said elongated member.

3. Electrical track expansion joint apparatus for placement in series-with a track which engages the shoe of a vehicle to carry electrical currents thereto, comprising:

a substantially zigzag-shaped member of a material of highelectrical conductivity, with a face portion for contacting said shoe and a pair of flanges extending rearwardly from laterally opposite sides of said face portion; and

a bar disposed within said member, said bar in sliding contact with a portion of said member and fixed with respect to one end of said member.

4. An electrical track expansion joint section comprising:

an elongated member of generally C cross section with a base and first and second flanges, said member having a first plurality of cuts extending through said first flange and said base up to the second flange and a second plurality of cuts interspersed with said first cuts along said member, said second cuts extending through said second flange and said base up to said first flange;

an elongated bracing bar disposed at least partially within said member and extending along the majority of the length thereof which includes cuts; and

means for fixing one end portion of said bar to one end of said member, the opposite end portion of said bar being in sliding contact with said member.

5. The electrical track expansion joint section described in claim 4 wherein:

said member includes lip portions extending toward each other from said flanges; and

said means for fixing includes a connecting member disposed against the outside of said lips, and fastener means extending between said bracing bar and said connecting member to draw them together with said lips between them.

6. Track apparatus comprising: first and second vehicle-engaging track sections which are substantially aligned but which have ends spaced from each other to form a gap;

an elongated member positioned to substantially bridge the gap between said spaced ends of said track sections, said member having a face for engaging an element of a vehicle, and having a plurality of slots extending substantially laterally from one edge of the member to a position spaced from the opposite edge, with alternate slots formed complementary to each other, whereby to form a zigzaglike member; and

bracing bar means extending along said member and having one end fixed with respect to one end of said member and an opposite end portion in slidable engagement with said member. 

1. Expansion joint apparatus for track sections which engage a vehicle comprising: an elongated member having a base defining a face for engaging an element of a vehicle and having a pair of flanges extending rearwardly from laterally opposite sides of said base, said member having a plurality of slots extending substantially laterally from one edge of the member to a position spaced from the opposite edge, with alternate slots formed complementary to each other, whereby to form a zigzag like member; and bracing bar means disposed within said elongated member, including one end fixed with respect to one end of said elongated member and an opposite end portion in slideable engagement with said elongated member.
 2. The expansion joint apparatus described in claim 1 wherein: said elongated member has lips extending from the rearward ends of said flanges toward each other; and said bracing bar means includes portions adjacent to the inner surfaces of the base, flanges and lips of said elongated member, whereby to resist twisting of said elongated member.
 3. Electrical track expansion joint apparatus for placement in series with a track which engages the shoe of a vehicle to carry electrical currents thereto, comprising: a substantially zigzag-shaped member of a material of high-electrical conductivity, with a face portion for contacting said shoe and a pair of flanges extending rearwardly from laterally opposite sides of said face portion; and a bar disposed within said member, said bar in sliding contact with a portion of said member and fixed with respect to one end of said member.
 4. An electrical track expansion joint section comprising: an elongated member of generally C cross section with a base and first and second flanges, said member having a first plurality of cuts extending through said first flange and said base up to the second flange and a second plurality of cuts interspersed with said first cuts along said member, said second cuts extending through said second flange and said base up to said first flange; an elongated bracing bar disposed at least partially within said member aNd extending along the majority of the length thereof which includes cuts; and means for fixing one end portion of said bar to one end of said member, the opposite end portion of said bar being in sliding contact with said member.
 5. The electrical track expansion joint section described in claim 4 wherein: said member includes lip portions extending toward each other from said flanges; and said means for fixing includes a connecting member disposed against the outside of said lips, and fastener means extending between said bracing bar and said connecting member to draw them together with said lips between them.
 6. Track apparatus comprising: first and second vehicle-engaging track sections which are substantially aligned but which have ends spaced from each other to form a gap; an elongated member positioned to substantially bridge the gap between said spaced ends of said track sections, said member having a face for engaging an element of a vehicle, and having a plurality of slots extending substantially laterally from one edge of the member to a position spaced from the opposite edge, with alternate slots formed complementary to each other, whereby to form a zig-zag like member; and bracing bar means extending along said member and having one end fixed with respect to one end of said member and an opposite end portion in slidable engagement with said member. 